Chile’s Central Workers Union, an umbrella organization consisting of several labor unions, launched a 2-day national strike Wednesday morning, supported by protesting students and the opposition Concertación coalition.

While the organizers insist the strike and its accompanying public protests are peaceful, fringe groups collided with police on Wednesday shortly after the strike began. Protesters in the capital of Santiago stoned buses and police responded with tear gas and water cannons. At least 18 flaming barricades were set up by protesters in the capital of Santiago and clashes between police and demonstrators occurred in Valparaíso and Concepción.

“We don’t want violence, our fight is not versus the police or to destroy commercial shops … our fight is to recover the right to education, on that we have been emphatic and clear,” said student leader Camila Vallejo.

The protests, which began in May of this year with students asking for educational reforms, have broadened to include demands ranging from a new constitution to a revamped tax system. The 48-hour strike is the first of its kind since the since the fall of a 27-year dictatorship in 1990.